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Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
pH-triggered block copolymer micelle-to-micelle phase transition
Li Xu1, Zhichen Zhu, Oleg V Borisov
1Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
Physical Review Letters
|October 2, 2009
Summary
We observed a pH-induced micelle-to-micelle phase transition in block copolymer solutions. This transition, occurring over a narrow pH range, significantly alters micellar size and aggregation.
Area of Science:
- Polymer Chemistry
- Physical Chemistry
- Materials Science
Background:
- Block copolymer micelles self-assemble in aqueous solutions.
- Polybasic polymer chains in micellar coronas are sensitive to pH changes.
Purpose of the Study:
- To experimentally observe and theoretically interpret a pH-induced phase transition in block copolymer micelles.
- To investigate the effect of pH on micellar structure and properties.
Main Methods:
- Dynamic light scattering (DLS)
- Static light scattering (SLS)
- Atomic force microscopy (AFM)
- Zeta potential measurements
Main Results:
- A sharp micelle-to-micelle phase transition was observed in a narrow pH range (DeltapH < 0.1).
- Significant changes in micellar hydrodynamic size and aggregation number were confirmed.
- Zeta potential measurements showed an abrupt change in polymer ionization at the transition pH.
Conclusions:
- pH is a critical factor controlling the self-assembly and phase behavior of these block copolymer micelles.
- The observed transition is driven by the ionization state of the polybasic corona chains.
- This study provides fundamental insights into pH-responsive polymer systems.
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